In optical transmission systems, particularly high capacity ones such as 2.5 or 10 Gb/s systems, and those incorporating optical amplifiers, there are typically new devices used within the plug-in units that compose the systems. New devices do not have an extensive history, and so conservative estimates must be used for the amount of degradation or change possible due ageing of that component over the 25 year lifetime of the equipment.
Another problem which has been identified is that one of these complicated units may be declared failed in the field, and when the repair team at the factory examines it there may be no fault found. The original fault may be due to unique environmental or system conditions that may make the fault difficult to reproduce in the factory. Units are commonly returned with minimal or missing paperwork describing the failure conditions. Customers may even send units back as failed, just to get them upgraded to the latest version while still under warranty.
In the field of optical transmission systems, it is known to monitor and remote information about parameters, such as received optical power and bit error rates, that are important to the operating company. Central Operations Systems collect the data and threshold crossing alarms. The operating company may use this information to schedule preventative maintenance of the system. Bellcore TR-253 is a technical requirement for SONET systems, and indicates analog parameters that are monitored eg laser currents and reported to the operating company. However, there has not been monitoring of lower level parameters which are of no direct interest to the operating company.
Storage of parameters or programs in non-volatile memory (NVM), such as FLASH is also known. Transmission systems, computer terminals, and other such systems, may save provisioned values or configurations in non-volatile FLASH memory within a unit. These then become the default parameters upon powering up the unit. For example, a computer terminal may save the default bit-rate, the number of bits per character, and the ASCII parity selection. However, there has been no suggestion of using such memory for saving the details of the internal analog parameters of the electrical and optical components of a unit.